The present invention is directed towards a filter and filter bag cage, particularly, a filter/cage arranged for use in industrial applications.
Filters have had wide commercial applications and utility in commercial industries. Filters generally involve the use of a filter media which, depending upon its construction, may or may not require a supporting structure. For example, filters made from a woven or non-woven textile material are often supported by way of wire cages. Filters can take on a variety of shapes. For example, as set forth in German Utility Model G 94 09 704.6, the disclosure of which is incorporated herein by reference, a filter bag is shown having a star shape. The filter support is also shown having a star shape about which the filter media is supported. The support is made typically from a wire made of metal or other suitable material. The filter is intended to remove particulate matter from a gas stream which flows from the outside of the filter into the filter with the particulate accumulated on the outside of the filter.
The particulate is then collected in a hopper at the base of the filter system. Due to the shape of the filter media, it provided for increased surface area for filtering compared to that of typically cylindrical bag filters.
Improvements upon such filter arrangements can be found in U.S. Pat. No. 5,951,726, the disclosure of which is incorporated herein by reference. In this patent a modular filter bag cage is described. As noted therein, such filters and their support members can be relatively large (i.e. 20-30 feet or more in length) depending upon the application. Thus, while the filter media may be folded for transportation or storage, etc., the cage, if rigidly constructed, did not have such an advantage. Accordingly, by making the cage modular in construction, provided for ease in storage, transportation, etc., and was readily assembled on site.
In certain applications, particularly power generating stations, foam coated filter media has been utilized on the inside surface which avoids contact with any supporting structure. These filters are used in gas solid separation such as flue gas filtration. These filters are typically cylindrical in construction and are used without cages, since the gas flow is from the inside of the filter and out, with an open end down and closed end up. The filter is subject to shaking to dislodge the dust which accumulates on the inside surface which is then collected.
Since such filters are used in large scale operations, their efficiency is important and has a significant effect on operating costs. Accordingly, there exists a need and a desire to improve the operation of such filters whilst avoiding in doing so the need to structurally modify the internal apparatus of the bag house in which they are employed.
It is therefore a principal object of the invention to provide for a filter which has improved operation efficiency.
It is a further object of the invention to provide for such a filter which provides for such efficiency without the need to modify the internal apparatus of the bag house in which it is used.
A yet further object of the invention is to provide such a filter which provides for increased operating capacity at a lower operating cost.
A still further object of the invention is to provide a filter which is versatile and may be modular in construction.
These and other objects and advantages are provided by the present invention. In this regard, the filter assembly provided includes a filter bag cage along with a corresponding filter. The filter assembly is intended to be used in a filtering apparatus or containment vessel. A plurality of filters are contained in the apparatus, usually positioned side by side extending upwardly from an inlet port or ports which feeds the gas stream which is to be filtered. The top of the filter assembly is typically capped so that the gas is filtered from the inside out with the particulate accumulating on the inside of the filter bag. The filter bag is provided with a plurality of pleats about its circumference. Its circumference is substantially the same as the cylindrical filters heretofore utilized and provides a ready replacement thereof. A filter bag cage is provided which is made of metal wire. The cage includes a plurality of wires which extend longitudinally while also extending radially inwardly so as to be positioned within the folds of the pleats. The cage serves to support the filter media including, particularly maintaining the pleated configuration. Due to the pleated arrangement, the filtration area is increased dramatically. This provides for improved operating efficiency.
In addition, the cage may be modular in construction such as that disclosed in the aforesaid United States Patent.